Marathon training

Marathon time predictor and finish time calculator

Enter a recent race result and PocketPacer predicts an equivalent marathon finish time, then turns it into a pacing plan you can actually run on race day. Works as a finish time calculator for 5K, 10K and half marathon too.

Open the calculator
  • Predicts marathon finish time from 5K, 10K or half marathon
  • Based on the proven Riegel power-law model
  • Equivalent finish times across every common race distance
  • Pair with a pacing plan for race day

How the model works

The predictor uses an exponent close to 1.06, which assumes that pace slows slightly as distance grows. It works best when both races are within roughly a 4× distance ratio — for example a half marathon predicting a marathon.

Short-distance predictions (5K predicting a marathon) tend to be optimistic and assume you have built the endurance to hold pace for several hours.

Use the prediction wisely

Treat the predicted time as a ceiling for fit, well-trained runners. If your long runs and weekly mileage are limited, target a slightly slower pace and aim for negative splits.

Frequently asked questions

How do marathon time predictors work?

They take a recent race result over any distance (typically 5K, 10K or half marathon) and use a power-law model to estimate what you can run over 42.195 km, assuming you have done the marathon-specific training.

How do I calculate an average finish time for a marathon?

The global average marathon finish time is around 4:30 for men and 4:55 for women. To estimate your own, enter a recent race in the predictor — it converts your current fitness into an expected marathon finish time using the Riegel model.

How accurate are marathon finish time predictions?

Predictions from a recent half marathon are usually within a few minutes of your real finish time if your training is marathon-specific. A 5K-based prediction is more optimistic and assumes you can hold pace for much longer.

How do I calculate race finish times for other distances?

Use the same predictor in reverse: enter any race result and PocketPacer outputs equivalent finish times for 5K, 10K, half marathon and marathon, so you can compare performances across distances.

What is a good marathon time?

Around 4:00–4:30 is a solid first marathon. Sub 4 is a popular target, sub 3:30 is strong, and sub 3 is competitive for most age groups.

How do I pace a marathon?

Aim for even or slightly positive splits and resist the urge to bank time. Most runners who blow up in a marathon went out 10–20 seconds per km too fast in the first 10 km.

Can I predict a marathon time without ever running one?

Yes — that is exactly what the predictor is for. Use your most recent race and PocketPacer estimates the marathon equivalent, then helps you build a pacing plan from it.

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